Insight into the Intermolecular Interaction and Free Radical Polymerizability of Methacrylates in Supercritical Carbon Dioxide

Abstract

High pressure in situ Fourier transfer infrared/near infrared technology (HP FTIR/NIR) along with theoretical calculation of density functional theory (DFT) method was employed. The solvation behaviors and the free radical homopolymerization of methyl methacrylate (MMA), methacrylate acid (MAA), trifluoromethyl methacrylate (MTFMA) and trifluoromethyl methacrylate acid (TFMAA) in scCO2 were systematically investigated. Interestingly, the previously proposed mechanism of intermolecular-interaction dynamically-induced solvation effect (IDISE) of monomer in scCO2 is expected to be well verified/corroborated in view that the predicted solubility order of the monomers in scCO2 via DFT calculation is ideally consistent with that observed via HP FTIR/NIR. It is shown that MMA and MAA can be easily polymerized, while the free radical polymerizability of MTFMA is considerably poor and TFMAA cannot be polymerized via the free radical initiators. The α trifluoromethyl group (–CF3) may effectively enhance the intermolecular hydrogen bonding and restrain the diffusion of the monomer in scCO2. More importantly, the strong electron-withdrawing inductive effect of –CF3 to C=C may distinctly decrease the atomic charge of the carbon atom in the methylene (=CH2). These two factors are believed to be predominantly responsible for the significant decline of the free radical polymerizability of MTFMA and the other alkyl 2-trifluoromethacrylates in scCO2.

Sulfonated Polybenzothiazoles Containing Hexafluoroisopropyl Units for Proton Exchange Membrane Fuel Cells

“…Both the 19 F NMR spectra of SMFA and SCFA (Figure S1b) showed signal peaks associated with −CF 3 at the same chemical shifts (−63 ppm), meaning that the two-step synthesis procedure did not destroy the F atomic groups, and the −CF 3 groups were well preserved after sulfonation and oxidation . As shown in the FT-IR spectra (Figure b), the absorption bands arising from −SO 3 Na were observed in both SMFA (1187, 1096, and 615 cm –1 ) and SCFA (1187, 1079, and 627 cm –1 ), whereas both SMFA and SCFA showed vibration peaks at 731 cm –1 , attributed to −CF 3 . ,− Peaks at 3168 and 1740 cm –1 were observed in SCFA, corresponding to the stretching vibration of −COOH. The results of NMR and FT-IR confirmed the successful synthesis of SMFA and SCFA.…”

Fluorine-Rich Zinc Oxoclusters as Extreme Ultraviolet Photoresists: Chemical Reactions and Lithography Performance

“…This decrease in the sensitivity could arise from various factors. The electron density on the terminal double bond of TFMA ligand is relatively low because of the neighboring electron-withdrawing CF 3 group . Previous studies have shown that introduction of a – CF 3 group at the α position decreases the rate of radical homopolymerization of the TFMA unit. , Different molecular packing of the oxoclusters in Zn­(TFMA) compared to its analogue Zn­(MA)­(TFA) or a reduced ratio of the solubility rates of the unexposed and exposed regions in the developer of choice can also contribute toward this observed decrease in the sensitivity.…”